Multimedia optical disc which can preserve the freshness of stored data, a reproduction apparatus for reproducing such optical disc and a reproduction method

ABSTRACT

A multimedia optical disc including data area and index area is provided. The data area includes objects each of which includes video data. The index area includes sub-areas. Each sub-area includes addresses of objects selected from the objects in the data area, a flag indicating a random reproduction of the objects selected, and a number of repeats of the random reproduction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical disc which storesinformation signals recorded and to a reproduction apparatus forreproducing such optical discs, more specifically to an optical discwhich stores multimedia data including digital moving picture data,audio data, and sub-picture data and to an optical disc reproductionapparatus for reproducing such optical discs.

2. Description of the Prior Art

Interactive software titles of various genres, such as aerobics,education and cooking, have been becoming increasingly noticeable oflate in the market of music and movie software titles. Such interactivesoftware titles include a plurality of branches during the reproductionof an optical disc, with the user being able to select the branch-toaddresses. Interactive software titles with simple mechanisms havealready been achieved for conventional video CD applications.

The first basic technique for the achievement of interactive software isdistributed recording. This refers, for example, to the division of aone-hour-long movie into, say, one-minute-long or five-minute-longsections which are recorded in separate areas on a spiral track, but notin a sequential order. The second basic technique is random accessing inwhich pieces of image information stored in separate areas are read inan arbitrary order using a plurality of sets of control information.Such sets of control information for random accessing each include areading order of the pieces of image information and address informationspecifying areas on the spiral track in which the pieces of imageinformation are recorded. Here, there can be as many sets of controlinformation as there are reading orders, with the user being able toselect a reading order from a menu displayed on the screen.

In this way, interactive software can provide several courses that canbe selected by the user using menus.

The following is a description of an interactive aerobics softwaretitle. This aerobics interactive software title has a plurality of shotsof an instructor doing different exercises, with several reproductionroutes being recorded in the title. These reproduction routes correspondto courses such as "make your waist slim," "make your legs slim," and"Lose five kilos" which can be selected by the user according to his/herpurpose. As one example, if the user selects the "make your legs slim"course, a series of shots including leg exercises, such as moving aroundwith rhythmical steps, jumping, raising right leg high, and raising leftleg high, are reproduced in succession.

If the user selects the "make your waist slim" course, a series of shotsconcerning waist exercises, such as twisting the waist to the right andleft or bending over, are reproduced in succession.

A menu which is displayed using image data and which includes thesecourse titles is displayed on the screen when the user loads the opticaldisc into the disc reproduction apparatus. Then, after the user hasselected a desired course from the menu in accordance with his/herpurpose, physical condition and quickness, the disc reproductionapparatus sequentially reads a plurality of shots in a reproductionroute which corresponds to the selected course. The read shots areconverted into image signals to be displayed on the screen. Here, byfollowing the instructor's movements which are displayed on the screen,the user can enjoy a desired exercise program in the comfort of theirown home. Should the user get bored with the selected program or wish totry something new, he/she can select another course and adjust its levelto suit him/her.

This kind of interactive software title recorded on an optical disc isideal for a housewife who is on a diet since she can select an exerciseprogram according to her physical condition and purpose and can exercisein between her chores. Such interactive software titles are alsobeneficial for company employees since they can complete a shortexercise program, such as before going to work, in order to compensatefor their lack of exercise.

Here, although conventional interactive software titles include aplurality of courses, these courses use a same reproduction order everytime. For this reason, users tend to get bored with the exerciseprograms provided by such titles. For the example of an aerobicssoftware title, the user can soon master the movements repeated in thelesson, so that such software titles quickly become routine to users.Here, there have been suggestions to provide a random reproductionfunction to the disc reproduction apparatus so as to avoid this tendencyfor the reproduced content to become routine. Such a random reproductionfunction, which is a function for reproducing pieces of data recorded ona storage medium in a random order, is widely used in the reproductionof music software. However, it is not desirable to use this function forinteractive software titles since the function regards every piece ofdata recorded on the optical disc as a potential reproduction object.This is to say, for the example of an interactive aerobics title,conventional random reproduction could have a menu, a shot of theinstructor raising his/her leg, and a shot of the instructor shakinghis/her arms displayed in that order, which would clearly make no senseto the user and would be of little value as exercise.

As can be clearly seen from the above example, for certain kinds ofinteractive title, the reproduction of pieces of data recorded on theoptical disc at complete random destroys the logical structure ofreproduction routes for each course. To avoid such disorderedreproduction, a user programming function may be used. Here, a userprogramming function is a function which invites the user to set thereproduction order of the course by himself/herself. Here, the manual orjacket of the software title can assist the user in setting such areproduction order, with most modern disc reproduction apparatuses beingequipped with this function. However, the setting of such functions tendto be rather complicated, so that users, such as housewives or officeworkers, may not have enough time for setting reproduction orders bythemselves. Such time-consuming procedures may end up only discouragingusers from using such aerobics software titles.

SUMMARY OF THE INVENTION

It is therefore the first object of the present invention to provide amultimedia optical disc and a reproduction apparatus which achieve aninteractive software title in which a plurality of pieces of movingpicture data in a course selected by the user can be reproduced in arandom order without making the user feel confused.

It is the second object of the present invention to provide a multimediaoptical disc and a reproduction apparatus which achieve an interactivesoftware title in which a plurality pieces of moving picture data in acourse selected by the user can be reproduced in a random order withoutrequiring prior programming by the user.

The above objects are achieved by a multimedia optical disc comprising adata area and an index area, the data area comprising a plurality ofobjects each of which includes video data, and the index area comprisinga plurality of sub-areas each of which includes addresses of objectsselected from the plurality of objects stored in the data area, a flagindicating a random reproduction of the objects selected, and a numberof repeats of the random reproduction.

With such a construction, the disc reproduction apparatus generatesrandom numbers and selects the addresses in the same sub-area at randomafter reading data recorded as above. As understood from the abovedescription, since each of the sub-areas includes a random reproductioninstruction and selected addresses, the objects to be selected at randomare limited to the addresses in each of the sub-areas. Here, if eachcourse such as "make your legs slim" and "make your waist slim"corresponds to a sub-area, the objects in each course are read andreproduced at random. As a result, the objects of each course arereproduced in arbitrary order, with the regularity of the course, whichis constructed under the logical structure of the interactive softwaretitle, being maintained. Accordingly, the reproduction of the opticaldisc does not make the user feel confused and provides the userfreshness for a long time by reproducing objects in a course in a randomorder, without requiring prior programming by the user.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings which illustrate a specificembodiment of the invention. In the drawings:

FIG. 1A shows an appearance of an optical disc used in the presentembodiment;

FIG. 1B is a cross section of the optical disc.

FIG. 1C is an enlarged detail of a part of the optical disc where theoptical spot is shone;

FIG. 1D shows pit sequences on information layer 109.

FIG. 2A shows a track arranged on the information layer of the opticaldisc;

FIG. 2B shows the construction of the physical sector of the informationlayer of the optical disc;

FIG. 3A shows the logical construction of the optical disc;

FIG. 3B shows the file area of the optical disc;

FIG. 4 shows the data construction of the Video Title Set;

FIG. 5 shows correspondence between moving picture materials, audiomaterials, and sub-title materials and the packs in video objects(VOBs);

FIG. 6 shows the construction of the Video Title Set managementinformation;

FIG. 7A shows the construction of the VOB address information table;

FIG. 7B shows the format of the PG reproduction mode;

FIG. 8 shows contents of moving picture data in VOBs;

FIG. 9 shows contents of descriptions in PGC information of Video TitleSet V2;

FIG. 10 shows the appearance of the reproduction apparatus used in thepresent embodiment;

FIG. 11 is a block diagram showing the construction of DVD player 1 usedin the present embodiment;

FIG. 12 is a block diagram showing the construction of systemcontrolling unit 93;

FIG. 13 is a main flowchart showing the process steps of systemcontrolling unit 93;

FIG. 14 is a flowchart showing the process steps of system controllingunit 93 at reproduction order determination;

FIG. 15 is a flowchart showing the process steps of system controllingunit 93 at shuffle reproduction;

FIG. 16 is a flowchart showing the process steps of system controllingunit 93 at random reproduction;

FIG. 17 shows images displayed on the screen when VOB#3 is read;

FIG. 18 shows images displayed on the screen when VOB#5 is read;

FIG. 19 shows images displayed on the screen when VOB#8 is read;

FIG. 20 shows the construction of the Video Manager; and

FIG. 21 shows a volume menu.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An optical disc storing multimedia data suitable for the presentembodiment is a digital video disc (DVD) with a diameter of 120 mm whichcan store about 4.7 GB of information on one side.

The following description is divided into a plurality of sections withthe section number written on the left-hand side and the title as shownbelow. (1) and (2) are the highest levels of sections. These sectionsbranch to sub-sections as indicated by the section numbers. The (1)family sections describe optical disc; the (2) family reproductionapparatus (disc reproduction apparatus).

(1.) Physical Construction of the Optical Disc

(1.1) Logical Construction of the Optical Disc

(1.1.1) Logical Construction . . . Video Title Set

(1.1.1.1) Video Title Set . . . Video Title Set Management Information

(1.1.1.2) Video Title Set . . . Video Object (VOB)

(1.1.2) Logical Construction . . . Video Manager

(2.1) Outline of the Disc Reproduction Apparatus

(2.2) Construction Element of the Disc Reproduction Apparatus

(2.2.1) Construction Element of the Disc Reproduction Apparatus . . .Construction of System Controlling Unit 93

(2.3) Operation of System Controlling Unit 93

(1.) Physical Construction of the Optical Disc

FIG. 1A shows an appearance of the DVD; FIG. 1B a cross-section of theDVD. FIG. 1C shows an enlarged circled part of FIG. 1B. Starting fromthe bottom, DVD 107 is formed of a first transparent substrate 108, aninformation layer 109, a second transparent substrate 111, a bondinglayer 110, and a print layer 112 on which a label is printed.

First transparent substrate 108 and second transparent substrate 111 areboth about 0.6 mm thick, that is, within a range of about 0.5 mm to 0.7mm, and are reinforcers which are made of the same material.

Bonding layer 110, formed between information layer 109 and transparentsubstrate 111, bonds these layers together.

A reflective membrane such a metal foil is attached to a surface ofinformation layer 109 where it is in contact with transparent substrate108. A high density of indented and protruding pits is formed in thisreflective membrane.

FIG. 1D shows pit shapes. The length of a pit ranges from 0.4 μm to 2.13μm. A whole series of pits form a spiral track with a radial distance of0.74 μm between the pit lines.

In FIG. 1C, information is retrieved by shining the laser beam 113 onthe series of pits and measuring changes in the reflection ratio of thelight spot 114.

The light spot 114 on a DVD has a diameter of around 1/1.6 times thediameter of a light spot on a conventional CD due to an increase in thenumerical aperture NA of the objective lens and a reduction in thewavelength λ of the laser beam.

DVDs of the physical construction described above can store about 4.7 GBof information on one side, which is almost eight times the storagecapacity of a conventional CD. As a result, it is possible to achieve agreat improvement in picture quality for moving pictures and to increasethe reproduction time from the 74 minutes which was possible with avideo CD to over two hours.

The substrate technique which has enabled this improvement in storagecapacity is a reduction of the spot diameter D of the laser beam. Here,spot diameter D is given by the equation "D=laser wavelength λ/numericalaperture of objective lens NA," so that the spot diameter D can bereduced by reducing the laser wavelength λ and by increasing thenumerical aperture of objective lens NA. It should be noted here that ifthe numerical aperture of objective lens NA is increased, comaticaberration occurs due to the relative inclination, known as "tilt",between the optical axis of the beam and the disc surface. In order tosuppress this phenomenon, DVDs use a transparent substrate of reducedthickness. Such a reduction in the thickness of the transparentsubstrate creates the problem of reduced physical durability for thedisc, although this problem can be overcome by reinforcing DVDs withanother substrate.

Data is read from DVDs using an optical system with a short wavelength(650 nm) red semiconductor laser and an objective lens whose NA(numerical aperture) is about 0.6 mm. If the thickness of thetransparent substrate is about 0.6 mm, a storage capacity of about 4.7GB can be achieved for one side of a 120 mm diameter optical disc. Withthis large storage capacity, there is more than enough capacity for awhole feature film to be recorded on one disc, with it further beingpossible for the manufacturer to include soundtracks in severaldifferent languages. Also, 4.7 GB of storage capacity achieved by thissubstrate technique is more than enough for a plurality of pieces ofmoving picture data or audio data.

FIG. 2A shows that a spiral track is formed on the information layerfrom an inner circle toward the circumference. Data is read from thespiral track in units of sectors. The sector includes, as shown in FIG.2B, the sector header area, the user data area, and the error correctioncode storing area.

The sector addresses in the sector header area are used to identify eachsector. The disc reproduction apparatus searches sectors to be read byusing the sector addresses.

The user data area stores 2 KB of data.

The error correction code storing area stores an error correction codefor the user data area in the same sector. The disc reproductionapparatus detects errors using the error correction code when the userdata area in the same sector is read, and also corrects the detectederrors. This secures the reliability of the data reading.

(1.1) Logical Construction of the Optical Disc

A spiral track formed with the series of pits includes a lead-in area, avolume area, and a lead-out area. FIG. 3A shows a spiral track re-formedinto a rectangle. As shown in this drawing, the lead-in area, volumearea, and lead-out area are included in a track in series, and theseareas are recognized by identification information included in thesector address. The lead-in area is located at the innermost position ofthe track; the lead-out area the outermost position. The lead-in areastores operation stabilization data which is used when the DVD playerstarts reading data from the optical disc. The lead-out area informs thereproduction apparatus of the end of reproduction and does not storemeaningful data.

The volume area stores digital data which makes up an application, andmanages the physical sector, as a logical block, to which the volumearea belongs. The logical blocks are identified by their serial numbers,which are put to consecutive physical sectors with the first physicalsector in the data recording area as number 0. "b301" shown in FIG. 3Ashows a group of logical blocks in the volume area. The logical blockshave their logical block numbers such as #m, #m+1, #m+2, #m+3, as shownin b301.

As shown in FIG. 3A, the volume area also includes a volume managementarea and a file area.

The volume management area stores the file system management informationconforming to ISO13346, which is used to manage a plurality of logicalblocks as files. The file system management information shows therelation between a plurality of file names and addresses of groups oflogical blocks. The disc reproduction apparatus achieves the disc accessin units of files by using the file system management information. Morespecifically, if a file name is given, the disc reproduction apparatusrefers to all the system management information to calculate all thegroups of logical blocks for the file, and accesses the groups oflogical blocks to fetch a desired piece of digital data.

FIG. 3B shows the file area. As shown in the drawing, the file areastores a Video Manager and a plurality of Video Title Sets. Each ofthese elements includes a plurality of consecutive files whose recordingpositions are calculated from the file system management information.The reason why the files are consecutive is that since the data size ofthe moving picture data is so large that if the data is included in afile, the file size exceeds 1 GB.

The Video Title Set stores a set of one or more DVD applications calledtitles. An example of such a set is a movie application in which twoversions of the same movie are included, namely, a theater version andan original cutting version. This is because since both versions sharemany parts of the same movie and can be used in effect when they aremanaged together as a set.

In FIG. 3B, Video Title Set V1 is an interactive software title called"aerobics." This interactive software title is achieved by the datastructure characteristic to the optical disc of the present embodiment.

Interactive software title "aerobics" includes three course titles,namely, "make your waist slim," "make your arms slim," and "totalfitness."

The Video Manager stores information on menus. The information is usedwhen the user selects a title among all the titles stored in theplurality of Video Title Sets to reproduce it.

(1.1.1) Logical Construction . . . Video Title Set

FIG. 4 shows the construction of the Video Title Set.

The Video Title Set includes a plurality of video objects (VOBs) and theVideo Title Set management information that manages the reproductionorder of the video objects (VOBs).

(1.1.1.1) Video Title Set . . . Video Object (VOB)

The video object (VOB) is multimedia data including digital movingpictures, digital sounds, image data, and management data for managingthese kinds of data. For example, in interactive software title"aerobics," each of VOB#1, VOB#2, VOB#3, . . . shown in FIG. 4 includesa scene of about 1-2 minutes such as the instructor moving around withrhythmical steps, jumping, raising right leg high, raising left leghigh, twisting her waist around right and left, and bending.

A video object (VOB) includes a plurality of VOB units aligned in timeseries. A VOB unit (VOBU) is a piece of reproduction data with a timeperiod ranging from about 0.5 to 1.0 seconds. A VOB unit includes, asshown in FIG. 4, a management information pack and a plurality of packs,namely, video packs, audio packs, and sub-picture packs. Each data packhas 2 KB of data. By re-constructing these packs, digital data sequencesof each video data, audio data, sub-picture data, and control data aregenerated. These digital data sequences re-constructed in types arecalled elementary streams. A VOB is also called a program stream or asystem stream each of which includes a plurality of elementary streams.

In FIGS. 4 and 5, all data packs are arranged regularly for the sake ofexplanatory convenience. However, since the reproduction apparatusfetches these packs after storing them in buffers, they can be arrangedirregularly, except the management information pack which should beplaced at the first position. Also the total number of packs in a VOBunit and the number of packs for each type may not be the same sincemoving picture data, audio data, and sub-picture data includevariable-length compressed data. Actually, each VOB unit has the numberof packs different from each other. Also, though the VOB unit of thepresent embodiment has two video packs, a normal moving picture includeshundreds of video packs since the rate of about 4.5 M bits/s is assignedto the moving picture data for transferring the data to the reproductionapparatus.

The video packs stored in the video object (VOB) form at least one pieceof digital video data called GOP (Group of Picture). GOP is a unit ofcompressed digital moving picture data after decompression, having about12 to 15 frames of image data. GOP is stipulated under MPEG2 (MovingPictures Experts Group, ISO11172, ISO13818).

FIG. 5 shows the relation between these packs in VOB and a scene. Thedrawing shows, from the top, a moving picture material for a scene, aVOB, three channels of audio materials, and two channels of sub-titlematerials. The downward arrows indicate how moving picture materials arerecorded in the data fields of the packs.

As shown in the drawing, a moving picture of about 0.5 seconds from thestart is coded into I-pictures (Intra-Pictures), P-pictures(Predictive-Pictures), and B-pictures (Bidirectionally predictivePictures). Then, the pictures are recorded in the data fields of videopacks #1 and #2 in VOBU#1. Note that though there are hundreds of videopacks in reality, it is assumed that there are two packs, as describedabove. Similarly, a moving picture of about 0.5 seconds to 1.0 secondsfrom the start is coded into I-pictures, P-pictures, and B-pictures.Then, the pictures are recorded in the data fields of video packs #3 and#4 in VOBU#2. Though it is not shown in the drawing, a moving picture ofabout 1.0 seconds to 1.5 seconds from the start is coded and recorded inthe data fields of video packs in the next VOB unit.

The relation between the dubbing in three channels and the data fieldsof the audio packs are described with reference to FIG. 5. As shown inthe drawing, the dubbing in three channels are encoded with the twomethods and recorded in the data fields of the audio packs in units ofabout 0.5 seconds. The dubbing of A channel is recorded in the datafields of audio pack A-1, A-2, A-3, . . . Note that since audio data andmoving picture data are synchronized with PTS, audio data and movingpicture data in the same VOB unit may not necessarily be used at thesame time. Actually, it may happen that the previous VOB unit stores apiece of audio data corresponding to a piece of moving picture data ofthe current VOB unit.

Similarly, the dubbing of B channel is recorded in the data fields ofaudio packs B-1, B-2, B-3, . . . in units of about 0.5 seconds; thedubbing of C channel in the data fields of audio packs C-1, C-2, C-3, .. . .

Hereinafter, pieces of data recorded in the data fields of audio packsA-C are respectively called audio data A, audio data B, and audio dataC. For example, English dubbing is set as audio data A, French dubbingis set as audio data B, and Japanese dubbing is set as audio data C,allowing the user to select a desired dubbing.

In FIG. 5, a VOB unit includes two sub-picture pack A and B. Therefore,the sub-titles in two channels are recorded in the data fields of thesesub-picture packs. For example, English sub-titles are included insub-picture data A, and French sub-titles are included in sub-picturedata B, allowing the user select any of the languages.

The management information pack is included in each VOB unit at itsstart, and its management information is effective while the VOB unit isreproduced. The management information pack stores a transfer rate whichis required during a VOB unit reproduction, a transfer rate required foreach of the moving picture stream, audio stream, sub-picture stream, anda buffer size.

The relation between the sub-picture packs and the managementinformation packs play important roles at interactive operations in aninteractive software title when the sub-picture packs includes menuseach of which includes several items. A management information pack inthe same VOB unit as sub-picture packs of a certain menu includeshighlight information which is used to perform a reproduction controlaccording to a cursor operation and a determination operation made bythe user against the certain menu. A representative "reproductioncontrol according to a determination operation" in the presentembodiment is a branch from a current reproduction route to anotherreproduction route. This "switch of reproduction route" is achieved bysetting highlight commands, which respectively correspond to the itemsof the certain menu, in the highlight information and executing ahighlight command when the management information pack is read by thedisc reproduction apparatus. With such setting, the reproduction routeis switched to another one in units of pieces of PGC information, whichis described later.

(1.1.1.2) Video Title Set Management Information

The Video Title Set management information stores information used formanaging the plurality of reproduction orders of the above-describedvideo objects (VOBs). In DVD, the information specifying a reproductionorder of a group of video objects (VOBs) is called a program chain(PGC). For example, the Video Title Set storing "aerobics" of thepresent embodiment has the Video Title Set management information whichstores a plurality of program chains specifying the scene developmentsfor "make your waist slim," "make your arms slim," and "total fitness."

FIG. 6 shows the construction of the Video Title Set managementinformation. As indicated by reference a5 in the drawing, a piece ofVideo Title Set management information includes a Video Title Setmanagement table, a Video Title Set unit title search pointer table, andPGC management information table.

The Video Title Set management table is the header information of theVideo Title Set management information and stores pointers for thestorage positions of the Video Title Set unit title search pointer tableand the PGC management information table.

The Video Title Set unit title search pointer table is the index of theplurality of program chains stored in the PGC management informationtable and specifies a pointer for the storage position of a programchain to be executed first in each title. For the present embodiment,the Video Title Set unit title search pointer table relates "make yourwaist slim," "make your arms slim," and "total fitness" of "aerobics" tocorresponding first pieces of PGC information.

The PGC management information table stores, as indicted by referencea6, a plurality of pieces of PGC information #1, #2, #3, #4, . . . #n.Each piece of the PGC information specifies a reproduction order of oneor more VOBs.

Which VOB to be read is specified by the VOB address information tableindicated by reference a7 in the drawing, and the reproduction order forreading the VOB is specified by the PG reproduction mode indicated byreference a9.

The VOB address information table stores a plurality of pieces of VOBaddress information to be reproduced. Each VOB address information, asshown in FIG. 7A, specifies a VOB reproduction time, an offset for a VOBposition in the Video Title Set, and the number of logical blocks in theVOB. By using this information, the disc reproduction apparatuscalculates the logical block number of all logical blocks which store aVOB when it reads the VOB.

The PG reproduction mode specifies the mode with which the VOBs writtenin the VOB address information table are reproduced. The VOBs can bereproduced with standard reproduction mode, random reproduction mode, orshuffle reproduction mode. While in standard reproduction mode, the VOBswritten in the VOB address information table are reproduced in order ofthe alignment in the table, in random or shuffle reproduction mode, theVOBs are reproduced at random.

While in random reproduction mode, each VOB may be reproduced twice ormore, in shuffle reproduction mode, each VOB is reproduced only once. Inother words, the random reproduction mode allows repetitions for theVOBs.

For example, suppose the VOB address information table includes VOBaddress information of VOB#1, VOB#2, VOB#3, VOB#4, and VOB#5. Alsosuppose it is specified that these VOBs are reproduced three times withshuffle reproduction mode, with different shuffle reproduction at eachreproduction. In this case, the VOBs may be reproduced in the followingorder:

VOB#5-VOB#1-VOB#3 (at first reproduction),

VOB#2-VOB#3-VOB#5 (at second reproduction), . . .

Now, suppose it is specified that VOBs are reproduced three times withrandom reproduction mode, with different random reproduction at eachreproduction. In this case, the VOBs may be reproduced in the followingorders:

VOB#5-VOB#5-VOB#3 (at first reproduction),

VOB#2-VOB#3-VOB#3 (at second reproduction), . . .

FIG. 7B shows the construction of the PG reproduction mode. The PGreproduction has eight bits. The most significant bit is called thefirst field and the rest of the bits (seven bits) are called the secondfield. The program chain is reproduced with random reproduction mode if"1" or higher value is specified in the second field and "0" isspecified in the first field. Also, the program chain is reproduced withshuffle reproduction mode if "1" or higher value is specified in thesecond field and "1" is specified in the first field. The second fieldspecifies the number of random or shuffle reproductions. The specifiednumber can be any of 1-127.

If "0" is specified in the second field, the program chain in reproducedwith standard reproduction mode.

FIG. 8 is a table showing contents of moving picture date in VOBs. Asshown in the drawing, VOB#1 includes a scene of the instructor movingaround with rhythmical steps, VOB#2 a scene of raising her right leg andleft leg high, VOB#3 twisting her waist with her arms stretchedhorizontally, VOB#4 jumping, etc. Each VOB includes a scene of about 2-3minutes.

FIG. 9 shows relation between each course and the contents of the PGCinformation.

As shown in this drawing, the first program chain of "make your armsslim" is PGC information #1. The VOB address information table of PGCinformation #1 includes 15 pieces of the VOB address information for 15VOBs such as VOB#3, VOB#5, and VOB#8 concerning exercises of arms among30 VOBs in total. Also, the shuffle reproduction mode is specified asthe PG reproduction mode, with the number of shuffle reproductions as"10." Generally, the number of combinations of r different objectsselected from n objects is denoted by the expression ^(n) C_(r) which isequal to n|/r|(n-r)|. Therefore, the number of ways generated by 10shuffles with 15 VOBs are obtained from the following equation:

    .sup.15 C.sub.10 =15|/10|*5|=3003.

As a result, 3003 different reproduction orders are generated for thisreproduction.

Also, the first program chain of "make your waist slim" is PGCinformation #2. The VOB address information table of PGC information #2includes 12 pieces of the VOB address information for 12 VOBs such asVOB#6, VOB#7, and VOB#9 concerning exercises of waist among 30 VOBs intotal. Also, the shuffle reproduction mode is specified as the PGreproduction mode, with the number of shuffle reproductions as "10."Therefore, the number of ways generated by 10 shuffles with 12 VOBs areobtained from the following equation:

    .sup.12 C.sub.10 =12|/10|*2|=66.

As a result, 66 different reproduction orders are generated for thisreproduction.

The first program chain of "total fitness" is PGC information #3. TheVOB address information table of PGC information #3 includes 5 pieces ofthe VOB address information for 5 VOBs such as VOB#1, VOB#4, and VOB#6.The random reproduction mode is specified as the PG reproduction mode,with the number of random reproductions as "3." Generally, the number ofrepeated combinations of r different objects selected from n objects isdenoted by the expression ^(n) H_(r) which is equal to ^(n+r-1) C_(r)equivalent to (n+r-1)|/r|(n-1)|. Therefore, the number of ways generatedby 3 random reproductions with 5 VOBs are obtained from the followingequation:

    .sup.5 H.sub.3 =(5+3-1)|/3|*4|=126.

As a result, 126 different reproduction orders are generated for thisreproduction.

"Total fitness" has less number of VOBs and reproduction cycles. Also,in this course, the same VOBs may be reproduced again and again.Therefore, even a very fat man/woman or a person with less quickness cankeep up with the course. On the contrary, "make your arms slim" had alot of VOBs and reproduction cycles. Also, the reproduction contentschange rapidly. Therefore, the course requires more quickness andphysical strength. The difference between the beginner course andadvanced course is also obvious in the figure. The number of ways forthe advanced course ("make your arms slim"), "3003" is about more than20 times that for the beginner course ("total fitness"), "126." Such acourse would satisfy even an "advanced" person in aerobics.

As apparent from the above description, the title creator can provideseveral courses of aerobics graded such as "beginner," "intermediate,"and "advanced" with an optical disc.

The first program chain of "digest" is PGC information #4. The VOBaddress information table of PGC information #4 includes 15 pieces ofthe VOB address information for 15 VOBs. The 15 VOBs are from the firstVOB to 15th VOB among the total of 30 VOBs of PGC information #4. Thenumber of cycles specifies "0." As a result, in "digest," the 15 VOBsfrom the first VOB to 15th VOB are reproduced sequentially in the order.This course is good for a person who just wants to look at the screenwithout doing actual exercises.

(1.1.2) Logical Construction . . . Video Manager

The Video Manager includes video objects (VOBs) and PGC managementinformation table, and the construction is almost the same as that ofthe Video Title Set. The VOB of the Video Manager differs from that ofthe Video Title Set in that the Video Manager is specialized in thevolume menu. The volume menu provides a list of all the titles includedin the optical disc so that the user can select one from the list. Thevolume menu is displayed on the screen after an optical disc is loadedin the disc reproduction apparatus and the optical pickup moves from thevolume management area to the volume area.

There are following differences between the Video Manager and the VideoTitle Set. First, while the VOB of the Video Title Set includes videopacks, audio packs, sub-picture packs, and a management information packas shown in FIG. 6, the VOB of the Video Manager includes the same kindsof packs for a menu. Secondly, the BRANCH commands of the Video Managercan specify any of a plurality of titles included in a plurality ofVideo Title Sets as a branch target.

FIG. 20 shows the construction of the Video Manager. As shown in thedrawing, the Video Manager includes the menu PGC management informationtable, the title search pointer table, and the menu video object.

The menu video object is a VOB specialized in the volume menu. That is,the menu video object includes a sub-picture pack for the volume menuand a management information pack which controls the reproductionaccording to the selection and determination operations by the user.FIG. 21 is the volume menu displayed on the screen. The menu videoobject includes a plurality of items, y611, y612, y613, and y616. Theitems represent titles such as "make your arms slim" and "make yourwaist slim" of "aerobics." A title is specified when the user selectsand determines an item in the menu.

The menu PGC management information table is PGC information specializedin the volume menu. The menu PGC management information table stores arecording section of the menu VOB which is read by the disc reproductionapparatus when the optical disc is inserted. The menu PGC information isread by the disc reproduction apparatus after an optical disc is loadedin the disc reproduction apparatus and the optical pickup moves from thevolume management area to the volume area. Then, the volume menu isdisplayed on the screen.

The title search pointer table is an index used to identify the VideoTitle Set and the title number of a title.

(2.1) Outline of the Disc Reproduction Apparatus

DVD players for reproducing optical discs are described with referenceto the drawings. FIG. 10 shows the appearances of DVD player 1, TVmonitor 2, and remote controller 91.

DVD player 1 includes an optical disc drive in which an optical disc canbe set through the slot on the front side.

Remote control receiving unit 92, also set on the front side of the DVDplayer, includes a light receiving device which receives infrared rayssent from the remote controller. Responding to an infrared ray from theremote controller by a user operation, remote control receiving unit 92outputs an interrupt signal indicating that a key signal has beenreceived.

On the rear side of the DVD player, video output terminal and audiooutput terminal are set. Through AV cords connected to the terminals,image signals reproduced by the DVD player can be output to TV monitor2. The user can enjoy the images reproduced by the DVD player on alarge-size TV such as 33-inch or 35-inch TV. As understood from theabove description, DVD player 1 in the present embodiment is intended tobe used as a household appliance connected to TV monitor 2, notconnected to a personal computer and the like.

Remote controller 91 outputs infrared rays as codes when key pads withsprings under them set on the controller are pressed by the user.

(2.2) Construction Element of the Disc Reproduction Apparatus

FIG. 11 is a block diagram showing the construction of the DVD playerused in the present embodiment. The DVD player includes optical discdrive 16, optical disc drive controlling unit 83, signal processing unit84, AV decoding unit 85, remote control receiving unit 92, and systemcontrolling unit 93. AV decoding unit 85 comprises signal separatingunit 86, video decoder 87, sub-picture decoder 88, audio decoder 89, andpicture mixing unit 90.

Optical disc drive 16 comprises a board on which an optical disc isplaced and spindle motor 81 for rotating the set optical disc. The boardmoves in and out of the cubic space by means of an eject mechanism whichis not shown in the drawing. The user places an optical disc on theboard ejected outside the DVD player. Then, the board moves into the DVDplayer, loading the optical disc.

Optical disc drive controlling unit 83 controls optical pickup andoptical disc drive 16 including spindle motor 81. Specifically, opticaldisc drive controlling unit 83 adjusts the motor speed according to atrack position specified by system controlling unit 93, moves opticalpickup by controlling the actuator of the pickup, then after a correcttrack is detected by servo control, waits for a desired physical sectorand reads signals continuously starting from desired position.

Signal processing unit 84 converts the signals read through opticalpickup into digital data by processing the signals with amplification,waveform shaping, conversion to binary, demodulation, error correction,etc., then stores the processed data in buffer memory 94 (describedlater) in system controlling unit 93 in units of logical blocks.

AV decoding unit 85 converts VOBs of digital data into the video signalsand audio signals.

Signal separating unit 86 receives the digital data transferred from thebuffer memory in units of logical blocks (packets), and classifies thedata into the management information data, moving picture data,sub-picture data, and audio data by identifying the stream ID andsub-stream ID of each packet. Signal separating unit 86 outputs themoving picture data to video decoder 87. Signal separating unit 86outputs the management information pack to system controlling unit 93.System controlling unit 93 sends a channel number for each of the audiomaterial and the sub-title material to signal separating unit 86. Signalseparating unit 86 outputs the audio data of the specified channel toaudio decoder 89; sub-picture data of the specified channel tosub-picture decoder 88. The audio and sub-picture materials of otherchannels are discarded.

Video decoder 87 decodes and extends the moving picture data sent fromsignal separating unit 86 and outputs the data to picture mixing unit 90as digital video signals.

Sub-picture decoder 88 decodes and extends the sub-picture data sentfrom signal separating unit 86 if the sub-picture data is image datacompressed with run length compression, and outputs the sub-picture datato picture mixing unit 90 in the same format as video signals.

Audio decoder 89 decodes and extends the audio data sent from signalseparating unit 86, and outputs digital audio signals.

Picture mixing unit 90 outputs NTSC (National Television SystemCommittee) Video Signals after mixing the outputs from video decoder 87and sub-picture decoder 88 according to the ratio specified by systemcontrolling unit 93.

(2.2.1) Construction Element of the Disc Reproduction Apparatus . . .Construction of System Controlling Unit 93

System controlling unit 93 controls entire DVD player 1, and isconstructed as shown in FIG. 12. System controlling unit 93 includesbuffer memory 94, management information pack buffer 95, embeddedprocessor 96, work buffer 97, and PGC information buffer 31.

Buffer memory 94 stores data which has been processed withamplification, waveform shaping, conversion to binary, demodulation,error correction, etc. From buffer memory 94, system controlling unit 93transfers the Video Title Set management information to another bufferwhich is not shown in the drawing; VOBs to signal separating unit 86 inunits of packs. Signal separating unit 86 sends back the managementinformation pack to system controlling unit 93.

Management information pack buffer 95 stores the management informationpack sent back from signal separating unit 86.

Embedded processor 96 includes a ROM which stores a control program ofDVD player 1, a work memory, and a CPU.

PGC information buffer 31 stores the PGC information currently selected.

Work buffer 97 stores "random number table" and "specified no. ofcycles" which are used in executions of the processes shown in theflowchart of FIG. 12 by system controlling unit 96.

(2.3) Operation of System Controlling Unit 93

Now, the operation of DVD player 1 is described with reference to FIG.13. FIG. 13 is a flowchart showing the process steps of systemcontrolling unit 93.

For inserting an optical disc, the user presses the eject button on thefront side of DVD player 1 and places the optical disc on the ejectedboard. Then, the board, with the optical disc on itself, moves into theDVD player and the optical disc loads in the DVD player.

At step 121, system controlling unit 93 is in a wait state judgingwhether an optical disc has been inserted. On receiving notificationfrom an optical sensor that an optical disc has been inserted, systemcontrolling unit 93 controls optical disc drive controlling unit 83 andsignal processing unit 84 so that the rotation of the disc is controlledwhile optical pickup is placed in the lead-in area. The disc rotation isstabilized while optical pickup is placed in the lead-in area. After therotation is stabilized, the optical pickup is moved from the lead-inarea toward the circumference and the volume management area is read.Then, according to the information read from the volume management area,a Video Manager is read (step 122).

System controlling unit 93 calculates the address of the program chainof the volume menu by referring to the menu program chain managementinformation in the Video Manager, then reproduces the program chain andstores it in PGC information buffer 31. Then, system controlling unit 93refers to the PGC information stored in the buffer and recognizes theVOB to be reproduced and calculates its address. System controlling unit93 outputs control signals to optical disc drive controlling unit 83 andsignal processing unit 84. Then the VOB is fetched from the optical discand reproduced, displaying the volume menu as shown in FIG. 21 on TVmonitor 2 (step 123).

It is supposed here that the user selects "make your arms slim" in themenu and performs the determination operation for the item, systemcontrolling unit 93 executes a BRANCH command specifying the titlenumber which is set as a highlight command corresponding to the title(step 125).

By executing the BRANCH command, system controlling unit 93 refers tothe title search pointer table of the Video Manager to determine theVideo Title Set (VTS) and the VTS title number. Then, system controllingunit 93 outputs control signals to optical disc drive controlling unit83 and signal processing unit 84, reproduces the Video Title Setmanagement information of the determined video title, and fetches theVideo Title Set unit title search pointer table of this information(step 126).

System controlling unit 93 determines the PGC information of the firstprogram chain in the title by referring to the fetched Video Title Setunit title search pointer table. Then, system controlling unit 93outputs control signals to optical disc drive controlling unit 83 andsignal processing unit 84, reproduces the determined PGC information,and stores the information in PGC information buffer 31. The PGCinformation of the volume menu is overwritten by the PGC information.System controlling unit 93 determines the video object to be reproducedand its address by referring to the stored PGC information, outputscontrol signals to optical disc drive controlling unit 83 and signalprocessing unit 84, and reproduces the determined video object.

After this, system controlling unit 93 determines and reproduces videoobjects in order according to the stored PGC information. Systemcontrolling unit 93 determines the next PGC information by referring tothe PGC connection information of the current PGC information when itcompletes reproducing the last video object specified in the current PGCinformation. Then, system controlling unit 93 discards the current PGCinformation and stores the next PGC information to continue thereproduction (step 128).

Note that DVD player 1 has a key for selecting an audio channel and asub-picture channel though the key is not shown in the drawing. Theaudio channel and the sub-picture channel selected by the user arestored in system registers (not shown in the drawings). When the videoobject is reproduced, system controlling unit 93 refers to the systemregisters to determine the effective channels and informs the channelsto AV decoding unit 85 by outputting the control signals. As a result,only an effective audio channel and a sub-picture channel provides datato be output together with the moving picture data.

(2.3.1) Operation Example 1 . . . Reproduction Control for Video TitleSet V1

Software control of Video Title Set V1 by system controlling unit 93 isdescribed with reference to FIGS. 14 and 15.

It is supposed here that the user selects "make your arms slim." Whenthis happens, PGC information #1 is stored in PGC information buffer 31.At this stage, system controlling unit 93 determines reproductionorders. That is, system controlling unit 93 determines reproductionorders according to "PG reproduction mode" when control branches from amenu to a program chain. This process is achieved by the multiple branchas shown in the flowchart of FIG. 14. At step 140, the PG reproductionmode is read from the PGC information. At step 141, it is judged whetherbit pattern of the second field of the read PG reproduction mode is "0000000." The second field of PGC information #1 stores bit pattern "0001010,", indicating that the number of reproduction cycles is "10." Thisallows control to move to step 142.

At step 142, it is judged whether the bit pattern of the first field is"1." Since the first field of PGC information #1 stores bit pattern "1,"control moves to step 144.

Now, the operation of system controlling unit 93 is described withreference to FIG. 15. "Random number list" is a one-dimensional arrayused to store a history of random numbers generated in the shufflereproduction. "Total number n" is the number of pieces of VOB addressinformation written in the VOB address information table. For PGCinformation #1, the number is "15." "Specified number k" is a variablerepresenting the number of loops performed in steps 152 through 159.

The flowchart shown in FIG. 15 is the detailed flowchart of step 144 inFIG. 14. At step 150, the bit pattern of the second field representing"specified number" is read from the PGC information. Since the secondfield has seven bits, the second field can specify the number of cyclesranging from "0" to "127." At step 151, the random number list iscleared to zero. At step 152, random numbers for integers ranging from 1to 15 (the total number of VOBs) (0<r<n+1) are generated. Here, it issupposed that integer "3" is generated. Note that in the presentembodiment, it is supposed that "uniformly random numbers" aregenerated. For this type of random numbers, the VOBs written in the VOBaddress information table are uniformly selected. There are other randomnumbers such as "Gauss random numbers" which include arbitrarydistribution. The latter part of this course may be weighted so thatexercises in the latter part are selected more frequently.

At step 153, it is judged whether the generated integer "3" is writtenin the random number list. The integer is not written in the list sincePGC information has just been selected. At step 154, the third VOBaddress information in the VOB address information table is read. Atstep 155, a position in the spiral track in the optical disccorresponding to the logical block to be read is calculated according tothe VOB offset written in the VOB address information. Optical discdrive controlling unit 83 receives the track position and is instructedto move optical pickup to the record start position. Then, optical discdrive controlling unit 83 is instructed to control block reading.

At step 156, the process of step 157 is repeated for each logical blockin the VOB. The process of step 157 is to read data recorded at logicalblock #k through optical pickup and signal processing unit.

The data of the logical blocks in the VOB is sequentially read by thecontrol of optical disc drive controlling unit 83 and signal processingunit 84. The read data is separated and reproduced by AV decoding unit85. The moving picture separated at this stage is displayed on the TVscreen and audio data is output as sound. As a result, the screendisplays a shot of the instructor stretching her arms horizontally andturning them for several minutes as shown in FIG. 17. At the same time,a back ground music is output from the speakers. The user exercises inthe rhythm of the back ground music imitating the motion of theinstructor.

After the above process is repeated for each logical block in the VOBaddress information of VOB#3, control moves to step 158. At step 158,integer 3 is added to the random number list. At step 159, "1" issubtracted from the specified number k stored in the counter. At step160, it is judged whether the specified number k is more than "0." Atthe first cycle, control moves to step 152 to generate random numbers.

At step 152, random numbers for integers ranging from 1 to 15 (the totalnumber of VOBs) (0<r<n+1) are generated. Here, it is supposed thatinteger "3" is generated. At step 153, it is judged whether thegenerated integer "3" is written in the random number list. Therefore,control moves to step 152 to generate random numbers.

In this way, steps 152 to 153 are repeated while random numbers writtenin the list are generated. By checking the history written in the randomnumber list, redundant selections of already selected VOBs are avoided.

Suppose integer "5" is generated after a random number are generatedtwice. Since integer "5" is not written in the random number list,control moves to step 154. The fifth VOB address information in the VOBaddress information table is read. At step 155, a position in the spiraltrack in the optical disc corresponding to the logical block to be readis calculated according to the VOB offset written in the fifth VOBaddress information. Optical disc drive controlling unit 83 receives thetrack position and is instructed to move optical pickup to the recordstart position. Then, optical disc drive controlling unit 83 isinstructed to control block reading.

At step 156, the process of step 157 is repeated for each logical blockin the VOB. The process of step 157 is to read data recorded at logicalblock #k through optical pickup and signal processing unit.

The data of the logical blocks in the VOB#5 is sequentially read by thecontrol of optical disc drive controlling unit 83 and signal processingunit 84. The read data is separated and reproduced by AV decoding unit85. The moving picture separated at this stage is displayed on the TVscreen and audio data is output as sound. As a result, the screendisplays a shot of the instructor stretching her arms horizontally thendropping them and crossing them at her belly for several minutes asshown in FIG. 18. At the same time, another back ground music is outputfrom the speakers. The user exercises in the rhythm of the back groundmusic imitating the motion of the instructor.

After the above process is repeated for each logical block in the VOBaddress information of VOB#3, control moves to step 158. At step 158,integer 5 is added to the random number list. After this addition, therandom number list has "3" and "5." At step 159, "1" is subtracted fromthe specified number k stored in the counter. At step 160, it is judgedwhether the specified number k is more than "0." At the second cycle,control moves to step 152 to generate random numbers.

At step 152, random number for integers ranging from 1 to 15 (the totalnumber of VOBs) (0<r<n+1) are generated. Here, it is supposed thatinteger "8" is generated. At step 153, it is judged whether thegenerated integer "8" is written in the random number list. The integerhas not been written in the list though "3" and "5" have been. Controlmoves to step 154. At step 154, the eighth VOB address information inthe VOB address information table is read. At step 155, a position inthe spiral track in the optical disc corresponding to the logical blockto be read is calculated according to the VOB offset written in the VOBaddress information. Optical disc drive controlling unit 83 receives thetrack position and is instructed to move optical pickup to the recordstart position. Then, optical disc drive controlling unit 83 isinstructed to control block reading.

At step 156, the process of step 157 is repeated for each logical blockin the VOB. The process of step 157 is to read data recorded at logicalblock #k through optical pickup and signal processing unit.

The data of the logical blocks in the VOB is sequentially read by thecontrol of optical disc drive controlling unit 83 and signal processingunit 84. The read data is separated and reproduced by AV decoding unit85. The moving picture separated at this stage is displayed on the TVscreen and audio data is output as sound. As a result, the screendisplays a shot of the instructor stretching her arms and raising themat her back as high as her chest for several minutes as shown in FIG.19. At the same time, another back ground music is output from thespeakers. The user exercises in the rhythm of the back ground musicimitating the motion of the instructor.

After the above process is repeated for each logical block in the VOBaddress information of VOB#3, control moves to step 158. At step 158,integer 8 is added to the random number list. At step 159, "1" issubtracted from the specified number k stored in the counter. At step160, it is judged whether the specified number k is more than "0." Atthe third cycle, control moves to step 152 to generate random numbers.

Each time it is judged that a random number has not been written in therandom number list at step 153, steps 152 to 159 are repeated. At step159, the count value is decremented by one at each end of a cycle, andcontrol moves to step 160.

As the count value is decremented by one at step 159, the value reachesthe lowest number, "0." When the count value is "0," it is judged as"Yes" at step 160 and the present flowchart ends. Through the aboverepetitions, the exercise shown by the instructor changes rapidly, andthe back ground music also changes. The user has done a good exercise ina short period of time.

Even if the user inserts the same optical disc and selects the samecourse next day, the different VOBs are reproduced. Since the userenjoys a course every day with rapid changes, the user can see theeffect of the exercise appearing in the body from day to day.

<random reproduction>

The random reproduction is achieved by a combination includingrepetitions. Therefore, the random reproduction is achieved by deletingthe check of the random number list from the flowchart of FIG. 15. FIG.16 shows the flowchart without the check of the random number list.

<Standard reproduction>

For the standard reproduction, the VOBs are reproduced in order as theyare written in the VOB address information table. For this purpose, onlysteps 156 to 157 in the flowchart of FIG. 14 are required.

At this stage, if the user selects "make your waist slim," a series ofshots of the instructor moving around with rhythmical steps, raisingright leg high, raising left leg high, and jumping are reproduced insuccession. That is, if the PGC information corresponding to "make yourarms slim" is read by the reproduction apparatus, the exercises of armsare selected at random and displayed on the screen. If the PGCinformation corresponding to "make your waist slim" is read by thereproduction apparatus, the exercises of waist are selected at randomand displayed on the screen.

As apparent from the above description, in the present embodiment, eachof the courses such as "make your arms slim" and "make your waist slim"corresponds to a piece of PGC information. A piece of PGC informationspecifies a reproduction order so that exercises from each course areselected at random and reproduced. Therefore, if the user selectscourse, concerned exercises are reproduced at random. With this randomreproduction, the user can enjoy different orders of exercises everymorning. This refreshes the user every morning and makes the userexercise with fresh feeling for the courses.

In the present embodiment, a VOB unit consists of a GOP. It is needlessto say that if the stored moving pictures have a reproduction time ofabout a second, a VOB unit may consist of two or three GOPs with veryshort reproduction time. In this case, a management information pack isset before such a plurality of consecutive GOPs. The managementinformation pack is effective for the plurality of GOPs.

In the present embodiment, the digital moving picture data under MPEG2is used for the moving picture data. However, other kinds of movingpicture data such as the digital moving picture data under MPEG1 and thedigital moving picture data with a conversion algorithm other than DCT(Discrete Cosine Transform) under MPEG may be used as far as the movingpicture data can form the multimedia data with the audio data and thesub-picture data.

In the present embodiment, the management information packs are includedin VOBUs in units of GOPs, being the units of reproducing moving picturedata. However, it is needless to say that if the method for compressingdigital moving picture changes, the unit of the management informationpack changes according to the compression method.

Now, a method for producing an optical disk used in the presentembodiment is described. The editor has to prepare master tapes such asvideo tapes of various shots filmed with video cameras and music tapesin which songs and sounds are recorded live. The moving pictures andsounds in the tapes are digitized and loaded into a nonlinear editingmachine. The editor creates menus and items using application programssuch as a graphic editor loaded in the editing machine, reproducingpictures and sounds frame by frame. The editor also creates managementinformation packs having highlight commands by using a GUI generator andthe like. Then, the editor encodes the above data under MPEG to createmoving picture data, audio data, sub-picture data, and managementinformation pack. Then, the editor creates the VOB unit and VOBs byusing the nonlinear editing machine. The editor assigns numbers to theVOBs. Also, the editor creates PGC information #1, #2, #3, . . . , #n,video title set unit title search pointer table, and video title setmanagement information. The editor loads these pieces of data into amemory in a workstation.

The data is converted into logical data sequences so that the data isrecorded in the file area. The logical data sequences are recorded intoa medium such as the magnetic tape, then converted to physical datasequences. The physical data sequences include volume data with ECC(Error Check Code), E-F conversion, data in the lead-in area andlead-out area. A master optical disk is produced by using the physicaldata sequences. Then, copies of the master optical disk are manufacturedby using a pressing machine.

Conventional CD manufacturing machines may be used for manufacturing theabove-constructed optical disk except a part of logical data sequencesrelated to the data construction of the present invention. Concerningthis point, please refer to Heitaro Nakajima and Hiroji Ogawa: CompactDisk Dokuhon, Ohmu Ltd. and Applied Physics Society Optics Meeting:Optical Disk System, Asakura Shoten.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to be notedthat various changes and modifications will be apparent to those skilledin the art. Therefore, unless such changes and modifications depart fromthe scope of the present invention, they should be construed as beingincluded therein.

What is claimed is:
 1. A multimedia optical disc comprising a data areaand an index area,the data area comprising a plurality of objects eachof which includes video data, and the index area comprising a pluralityof sub-areas each of which includes addresses of objects selected fromthe plurality of objects stored in the data area, a flag indicating arandom reproduction of the objects selected, and a number of repeats ofthe random reproduction.
 2. The multimedia optical disc of claim 1,whereineach of the plurality of sub-areas further includes a flagindicating whether to prohibit a redundant use of objects at the randomreproduction.
 3. The multimedia optical disc of claim 2, furthercomprisinga reproduction area for storing data for reproducing a menuwhich is to be displayed first on a display of a reproduction apparatus,wherein the data for reproducing a menu includes a plurality of menuitems which respectively correspond to the plurality of sub-areas. 4.The multimedia optical disc of claim 3, whereinthe reproduction areafurther comprises management information, wherein the managementinformation includes a plurality of identifiers of the plurality of menuitems and a plurality of addresses of the plurality of sub-areas.
 5. Themultimedia optical disc of claim 4, comprisinga first transparentsubstrate and a second transparent substrate which are bonded with aninformation layer in between, each of the first transparent substrateand the second transparent substrate having a thickness range of 0.5 mmto 0.7 mm, and the information layer including the index area and thedata area.
 6. The multimedia optical disc of claim 1, whereinthe indexarea further comprises a certain sub-area which includes certainaddresses of certain objects selected from the plurality of objectsstored in the data area, wherein the certain addresses are aligned inorder of reproduction.
 7. The multimedia optical disc of claim 6,further comprisinga reproduction area for storing data for reproducingan initial menu which is to be displayed first on a display of areproduction apparatus, wherein the data for reproducing a menu includesa plurality of menu items which respectively correspond to the pluralityof sub-areas.
 8. The multimedia optical disc of claim 7, comprisingafirst transparent substrate and a second transparent substrate which arebonded with an information layer in between, each of the firsttransparent substrate and the second transparent substrate having athickness range of 0.5 mm to 0.7 mm, and the information layer includingthe index area and the data area.
 9. A multimedia optical disccomprising a data area and an index area,the data area comprising aplurality of objects each of which includes at least video data, and theindex area comprising: a plurality of first sub-areas each of whichincludes addresses of objects selected from the plurality of objectsaccording to a first standard, a flag indicating a random reproductionof the objects selected, and a number of repeats of the randomreproduction; and a plurality of second sub-areas each of which includesaddresses of objects selected from the plurality of objects according toa second standard, a flag indicating a random reproduction of theobjects selected, and a number of repeats of the random reproduction.10. The multimedia optical disc of claim 9, whereineach of the pluralityof first sub-areas and the plurality of second sub-areas furtherincludes a flag indicating whether to prohibit a redundant use ofobjects at the random reproduction.
 11. The multimedia optical disc ofclaim 10, further comprisinga reproduction area for storing data forreproducing a menu which is to be displayed first on a display of areproduction apparatus, wherein the data for reproducing a menu includesa plurality of menu items which respectively correspond to the pluralityof sub-areas.
 12. The multimedia optical disc of claim 11, whereinthereproduction area further comprises management information, wherein themanagement information includes a plurality of identifiers of theplurality of menu items and a plurality of addresses of the plurality ofsub-areas.
 13. The multimedia optical disc of claim 12, comprisingafirst transparent substrate and a second transparent substrate which arebonded with an information layer in between, each of the firsttransparent substrate and the second transparent substrate having athickness range of 0.5 mm to 0.7 mm, and the information layer includingthe index area and the data area.
 14. A reproduction apparatus forreproducing a multimedia optical disc, the multimedia optical disccomprising a data area and an index area, the data area comprising aplurality of objects each of which includes video data, and the indexarea comprising a plurality of sub-areas each of which includesaddresses of objects selected from the plurality of objects stored inthe data area, a flag indicating a random reproduction of the objectsselected, and a number of repeats of the random reproduction, whereinthereproduction apparatus comprises: an optical pickup for opticallyreading the plurality of objects from the multimedia optical data; anoptical disc driving mechanism for driving the multimedia optical discso that the optical pickup moves to a desired area on the multimediaoptical disc; an AV decoder for decoding the video data in the readobjects; first controlling means for controlling the optical discdriving mechanism so that contents of a desired sub-area are read;random number generating means for generating random numbers, whereinthe random number generating means is activated according to the flagindicating a random reproduction included in the read contents of thedesired sub-area; first address reading means for reading at least oneaddress from the addresses included in the desired sub-area by using thegenerated random numbers; and a second controlling means for controllingthe optical disc driving mechanism and the video decoder so that objectscorresponding to the read address are reproduced.
 15. The reproductionapparatus of claim 14, further comprising:a counter for countinggenerations of random numbers by setting the number of repeats of therandom reproduction described in the desired sub-area as an upper limitvalue for counting; and count value judging means for judging whether acount value of the counter exceeds the upper limit value each time arandom number is generated, wherein the random number generating meansis activated repeatedly unless the count value exceeds the upper limitvalue.
 16. The reproduction apparatus of claim 15, furthercomprising:flag judging means for judging whether the flag indicating arandom reproduction is included in the read contents of the desiredsub-area; second address reading means for reading the addresses fromthe desired sub-area if the flag is not included in the read contents;managing means for activating the random number generating means if theflag is included in the read contents and activating the second addressreading means if the flag is not included in the read contents, whereinthe second controlling means controls the optical disc driving mechanismand the video decoder so that at least one address is received from bothof the first address reading means and the second address reading meansand the received address is reproduced.
 17. The reproduction apparatusof claim 16, whereinthe multimedia optical disc further comprises areproduction area for storing data for reproducing a menu which is to bedisplayed first on a display of a reproduction apparatus, wherein thedata for reproducing a menu includes a plurality of menu items whichrespectively correspond to the plurality of sub-areas, wherein thereproduction area further comprises management information, wherein themanagement information includes a plurality of identifiers of theplurality of menu items and a plurality of addresses of the plurality ofsub-areas, wherein the reproduction apparatus further comprises: menuitem receiving means for receiving a desired menu item selected from themenu; and third address reading means for referring to the managementinformation and reading a address corresponding to the desired menuitem, wherein the first controlling means controls the optical discdriving mechanism and the video decoder so that at least one object isreproduced based on the read address.
 18. A reproduction method forreproducing a plurality of objects based on a plurality pieces ofreproduction control information, wherein each of the plurality ofobjects includes video data, wherein each of the plurality pieces ofreproduction control information includes a set of identifiers each ofwhich corresponding to an object, a flag, and a number of reproductionrepeats, whereinthe reproduction method comprising: a first reading stepfor reading a piece of the plurality pieces of reproduction controlinformation; a random number generating step for generating a randomnumber according to "on" and "off" of the flag included in the piece ofreproduction control information read in the first reading step; adetermining step for determining an identifier among the set ofidentifiers by using the random number generated in the random numbergenerating step; a second reading step for reading an object specifiedby the identifier determined in the determining step; a decoding stepfor decoding the video data included in the read object; and a repeatingstep for activating the random number generating step repeatedly basedon the number of reproduction repeats included in the piece ofreproduction control information read in the first reading step.